Electric switch



UCL 3, 1929 c. w. HEWLETT 1,731,133

Y ELECTRIC SWITCH Filed Oct. 26, 1927 Inven'or' CIaPenceW Hewle,

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Patented Oct. 8, 1929 UNITED STATES PATENT OFFICE CLARENCE W. HEWLETT,OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, ACORPORATION F NEW YORK ELECTRIC SWITCH Application led October 26, 1927.Serial No. 228,888.

My invention relates to electric switches and particularly thoseoperated in an insulating liquid. An object of my invention is theprovision of an improved switch of this type which is especially adaptedfor the control of large capacity power circuits and which willsuccessfully interrupt the circuit in a minimum time after the contactsbegin to separate. My invention will be better understood from thefollowing description taken in con-l nection with the accompanyingdrawing, and its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 is a cross sectional v1ew of a switchin closed circuit position embodying my invention; Fig. 2 is afragmentary sectional view taken on the line 2-2 of Fig. 1; and Fig. 3is an elevation of the switch in open circuit position drawn to areduced scale.

In the drawing the base or frame 1, shown mounted upon the liquid andgas receptacle 2, is provided with a central opening into which issecurely fastened the casing 3 of insulating material. Fixed in thiscasing is the contact 4 secured by the nut 5 and having the termin al 6and slidably mounted in the casing is the cooperating movable contactrod 7. The rod lits loosely in the casing but passes through a stuffingbox 8 fastened into the outer end thereof. On the stuffing box 8 issecured the band 9 to which is fastened the other terminal, not shown.In the closed circuit position of the switch the contact rod 7 is heldfirmly against the fixed contact 4 by the levers 11 pivotall mounted onthe rods 12 and engaged by the coil springs 13. y

The contacts are caused to separate and any arc that may be drawntherebetween is ex- 50 nected at their upper ends by the plate 21 andtinguished by means of an insulating fluid secured at their lower endsto the frame 1 form guides for the weight 22 which in falling strikesthe plunger 17. The weight is shown retained in its raised position bythe latch 23 adapted to be released by the electromagnet 24., At the endof the downward stroke of the plunger the weight and plunger are broughtto rest and the shock thereof cushioned by the engagement of the plate25 on the plunger with the rubber pads 26 on the supports 27. Below thecasing 3, the passage 15 continues straight on down through theinsulation 30 terminating in a Valve seat upon which the valve 31normally rests. The receptacle 2 encloses the valve 3l and is shownprovided with insulation lining 32 to prevent an arc that may bedeflected past the valve from reaching the metallic walls. Plate 33supported through the insulation cylinders 34 from the insulated rods 35carries the valve and the coil spring 36 by which the valve is closed.Vent opening 38 is provided at the top of the receptacle 2 for theescape of gas and a lower opening 39 serves for the admission orwithdrawal of insulating liquid to maintain the desired level thereof inthe receptacle.' I

After each circuit opening operation the weight 22 is raised by hand orsuitable means until the latch 23 is engaged. The plunger 17 also may beraised by hand or may be raised by pumping the insulating liquid throughthe pipe 40 past the check valve 41 and into the passage 15. Theplunger' is shown hollow for lightncssand Afor collect-l ing gas, avalved vent 42 being provided at the upper end of it to permittheescape-of any gas that collects therein.

The outward movement of contact rod 7 is checked by the buer comprisingthe plate 45 supported by the Irods 12, the shock being cushioned by therubber plate 46. Se-

cured to the outer side of the plate 45 is thesolenoid 48 which whenenergized is adapted to drive its plunger 49 inward against the s ring50 to return the rod 7 to such'a position that the levers 11 may engageover the end of the rod and complete the inward stroke.

When the switch is to be operated to open the circuit controlledthereby, the weight 22 is released by moving the latch manually or bythe soleneid 24 which'if desired may be load responsive. rlhe energyacquired by the falling Weight is delivered to theplunger which producesa sudden high pressure of the insulating liquid. The contact rod 7 irstis driven outward to the limit of its Inovement, the rod beingpreferably hollov't7 to lighten it, and immediately after the valve 31is forced open thus releasing the liquid'after the contacts haveseparated. As a result a stream of cool insulating liquid is forced at ahigh velocity directly across any arc that is drawn between thecontacts. The iiow of liquid is through a straight passage wherefriction and eddy losses are a minimum and the arc and hot gases arecarried away from both contacts, thereby avoiding all possible burningthereof. These features, together with the advantage of the high speedof the initial separation of the contacts, result in the completeinterruption of the circuit inl less than one half cycle of a sixtycycle circuit.

I have chosen the particular embodiment described above as illustrativeof my invention and it will be apparent that various modifications maybe made without dseparting from the spirit and scope of my inventionwhich modifications I aim to cover by the appended claims. y

What I claim as new and desire tosecure by Letters Patent of the UnitedStates is:

1. An electric switch comprising relatively movable contacts, means forsubjecting the contacts to a sudden pressure of insulating fluid tocause separation thereof, means providing a path of escape for the fluidpassing between the contacts extending transversely to the direction ofrelative movement thereof, and valvey means controlling said path..

constructed to open in response to a predetermined pressure of thefluid.

2. An electric switch of theliquid brea type comprising a pair ofrelatively movable contacts, a casing in which said contacts are mountedhaving a passage for insulating liquid extending transversely vthroughthe path of relative movementof the contacts, means for producing asudden pressure of said liquid to separate the contacts and yieldingmeans for normally closing said passage.

3. An electric switch of the liquid break type comprising a pair ofcooperating contacts, a casing' in which said contacts are mounted forrelative movement, said casing having a passage containing` insulatingliquid extendingat right angles through the path of relative movement ofthe contacts, means for producing a sudden pressure of liquid in thepassage'at one side of the contacts and a yieldingly closed valvecontrolling the escape of liquid from the passage at the other side ofthe contacts.

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4. An electric switch of the liquid break type comprising an insulatingcasing, a con- -tact mounted therein, a cooperating movable contactmounted therein for movement longitudinally out of engagement with theother contact, said casing having, a transverse passage containinginsulating liquid extending in opposite directions from said contacts,means for exerting pressure on the liquid at one side of the contacts, areceptacle at the other sidethereof and a spring pressed valvecontrolling the flow of liquid from the passage to the receptacle.

5.\An electric switch of the liquid break type. comprising an insulatingcasing, a fixed contact mounted therein, a cooperating contact rodmounted to slide longitudinally therein, said casing having a straighttransverse passage containing insulating liquid and arranged tointersect an arc drawn between the contacts, means comprising a. plungerfor producing a sudden pressure of liquid at one end of said passageadapted to separate the contacts and a spring closed valve at the otherend of the passage adapted to release the liquid after the contacts haveseparated.

6. An electric switch comprising relative- ,ly movablev cooperatingcontacts, means for subjecting the contacts to fluid pressure to cause arapid separation thereof, means forming a path'of escape for the' iiuidfrom the contacts and means for preventing the escapel of Huid until thepressure thereof reaches a predetermined value.

7. An electric switch comprising relatively movable cooperatingcontacts, a contact supporting member in which one of said contacts ismounted to .move longitudinally, said member having a transverse passagetherethrough containing yinsulating liquid and arranged adjacent thepoint of separation of the contacts, means for producing a pressureofthe liquid at one side of the contacts and means forpreventing theescape ofthe liquid from the opposite side of the l contacts until abeen reached.

8. electricswitch comprisingan insulating casing having a bore, a fixedcontact mounted in said casing, a contact rod fitting said bore andadapted to'b'e separated from the fixed contact, said ycasing having atransverse passage containing insulating liquid adjacent thepoint ofseparation of said contacts, a spring closed valve closing one end ofsaid passage and means for producing a sudden pressure of liquid at theother end of said passage.

In witness whereof, I Ihave hereunto set my hand this 25th day ofOctober` 1927 .i

CLARENCE W. HEWLETT.

predetermined pressure has

